U.S. patent number 5,100,426 [Application Number 07/386,998] was granted by the patent office on 1992-03-31 for catheter for performing an atherectomy procedure.
This patent grant is currently assigned to FTS Engineering, Inc.. Invention is credited to Jeddy D. Nixon.
United States Patent |
5,100,426 |
Nixon |
March 31, 1992 |
Catheter for performing an atherectomy procedure
Abstract
A catheter for performing an atherectomy procedure to remove
plaque from an artery is disclosed. The catheter includes a plaque
cutting head having an outer shell of thin flexible material
generally cylindrical in cross-section and shaped to engage plaque
in an artery. The outer shell has a plurality of openings through
which the plaque will enter the shell as the shell is forced
against the plaque. A cutter rotates inside the shell to cut the
plaque that enters into the shell into small pieces as the catheter
is pushed through an artery. A motor drive elongated drive shaft
rotates the cutter.
Inventors: |
Nixon; Jeddy D. (Houston,
TX) |
Assignee: |
FTS Engineering, Inc. (Houston,
TX)
|
Family
ID: |
23527998 |
Appl.
No.: |
07/386,998 |
Filed: |
July 26, 1989 |
Current U.S.
Class: |
606/170; 604/22;
606/159 |
Current CPC
Class: |
A61B
17/320758 (20130101) |
Current International
Class: |
A61B
17/22 (20060101); A61B 017/32 () |
Field of
Search: |
;604/22 ;606/170,169,159
;128/804 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Article describing "Roto-Rooter" described in the Apr. 1988 issue
of Popular Science. .
Article taken from Houston Chronical newspaper dated Sunday, Jun.
25, 1989..
|
Primary Examiner: Rosenbaum; C. Fred
Assistant Examiner: Lewis; William
Attorney, Agent or Firm: Vaden, Eickenroht, Thompson &
Boulware
Claims
What is claimed is:
1. A catheter for performing an atherectomy procedure to remove
plaque from an artery comprising a plaque cutting head including an
outer shell of thin flexible material generally cylindrical in
cross section and shaped to engage plaque in an artery, said outer
shell having a plurality of openings through which the plaque will
enter the shell as the shell is forced against the plaque, and a
cutter rotating inside the shell to cut the plaque that enters into
the shell into small pieces as the catheter is pushed through an
artery, an elongated drive shaft for rotating the cutter, piezo
electric crystals mounted on the drive shaft to cause the cutting
head to vibrate, means for supplying the crystals with electrical
energy to cause such vibration, and a motor for rotating the shaft
and the cutter.
2. The catheter of claim 1 further provided with a tubular drive
shaft and a first elongated tubular member extending through the
drive shaft and attached to the outer shell to resist rotation of
the outer shell due to counter torque.
3. The catheter of claim 2 further provided with a second elongated
tubular member extending over the drive shaft and having an inner
diameter larger than the outside diameter of the drive shaft to
provide an annular space and means to reduce the pressure in the
annular space below ambient pressure to cause the pieces of plaque
removed from the artery by the cutter to flow into the annular
space along with some blood.
4. The catheter of claim 1 in which the outer shell and cutter are
cone-shaped.
5. The catheter of claim 1 in which the cutter includes an outer
section positioned to rotate close to the inner surface of the
outer shell and having a plurality of openings that move past the
openings in the outer shell so that an edge of each opening in the
outer section of the cutter will cut off a portion of the plaque
extending into the opening in the outer shell.
6. The catheter of claim 5 in which the openings in the outer shell
and the outer section of the cutter are position so that not all of
the edges of the openings in the cutter are cutting plaque at any
one time.
7. The catheter of claims 5 or 6 in which the cutter can be
positioned in the outer shell so that all openings in the outer
shell are closed.
Description
This invention relates to catheters generally and in particular, to
a catheter for performing an atherectomy procedure.
For many years a procedure called angioplasty has been used to open
arteries clogged with plaque. The catheter carries a balloon to the
location where the artery is clogged. The balloon is inflated to
flatten the plaque against the vessel wall and form a larger
opening through the artery. Angioplasty is widely accepted by the
medical profession and these procedures have successfully saved or
improved the quality of many lives for the past several years. It
does have some problems however. Emerging statistics tend to show
that treated vessels, veins, or arteries, though expanded,
frequently revert to critical restrictive conditions.
Atherectomy is a procedure that utilizes a cutting tool to remove
hardened atheroma from the lumen (channel) of arteries. Atheroma is
a mass of plaque of degenerated, thickened arterial intima
occurring in atherosclerosis. This is the condition in which
deposits of plaque containing cholesterol lympoid materials and
lipophages are formed and retained on the walls of arteries with
great tenacity.
Thus, it is an object of this invention to provide a catheter for
performing an atherectomy procedure that will cut the plaque from
the walls of an artery into very small pieces and remove the plaque
cuttings from the artery through a passageway in the catheter.
It is a further object of this invention to provide such a catheter
that will leave the walls of the artery smooth to discourage and
delay another build up of plaque.
It is a further object of this invention to provide such a catheter
that will vibrate the cutting head of the catheter along the
longitudinal axis of the artery to reduce the chances of the
cutting head becoming stuck in the artery and to improve the
cutting action of the cutting head.
It is a further object of this invention to provide such a catheter
with a cutting head having an outer shell of thin flexible material
having openings therein through which plaque will protrude when the
outer shell is forced against the plaque and a cutter rotating in
the outer shell to shave off the plaque that protrudes through the
openings, said cutter being designed to close all of the openings
when the cutter is in one position relative to the outer shell and
to limit the openings that are open at any given time as the cutter
rotates relative to the outer shell so that only a portion of the
plaque is being severed from the wall of the artery at any given
time thereby reducing the torque required to rotate the cutter.
It is another object and feature of this invention to provide such
a catheter with a passageway extending from the cutting head to a
location outside the patient and means to lower the pressure in the
passageway below the ambient pressure in the artery so that blood
will flow out of the patient through the passageway carrying the
severed plaque with it.
It is another object and feature of this invention to provide a
check valve in the passageway through which the blood flows out of
the patient to allow the pressure to be increased in the passageway
to stiffen the catheter when the catheter is being inserted into
the artery.
It is a further object of this invention to provide such a catheter
having a cutting head with an outer shell of thin flexible material
having openings therein and a hollow cutter located inside the
outer shell having a outside surface adjacent the inside surface of
the outer shell, said cutter having openings positioned similarly
to the openings in the outer shell so that the edges of the
openings in the cutter combine with the edges of the opening in the
outer shell like scissor blades to shear the plaque protruding into
the outer shell from the wall of the artery.
These and other objects, features, and advantages of this invention
will be apparent to those skilled in the art from a consideration
of this specification including the attached drawings and appended
claims.
FIG. 1 is a side view partially in section and partially in
elevation, of one embodiment of the cutting head of this invention,
which is located at the forward end of the catheter.
FIG. 2 is an end view of the cutting head of FIG. 1.
FIG. 3 is another, and probably the preferred embodiment, of the
cutting head of this invention.
FIG. 4 is a sectional view taken along line 10-10 of FIG. 3.
The cutting head shown in FIG. 1 includes outer shell 10 and cutter
12 located inside the outer shell. The cutter includes central
tubular section 12a and outer section 12b that encircles the
central tubular section and is spaced therefrom except at the
forward end where the two are connected. Inclined disc 12c extends
between the central section and the rearward end of the outer
section to connect the two and support the outer section.
The outer section of the cutter is shaped to match the shape of the
outer shell and is positioned to be in sliding engagement with the
outer shell when the outer shell is moved into engagement with the
plaque in an artery. The outer shell is shown in the drawings to be
about as thick as the outer section of the cutter, but, actually it
will be much thinner about 0.001 inch. The cutter has a plurality
of openings 14 in the outer section and the outer shell has a
plurality of openings 18 that are positioned for the openings in
the cutter to pass over the openings in the outer shell as the
cutter is rotated. The edges of the openings in the cutter act as
cutting blades that cross the openings in the outer shell in the
manner shown in FIG. 2 and sever the plaque extending into the
opening in the outer shell like scissors.
As shown in FIG. 2, plaque is being cut in only two openings in the
outer shell. The other two openings that are shown in this figure
are closed by the outer section of the cutter. This arrangement
reduces the amount of torque necessary to rotate the cutter, which
is a very important consideration since all of the parts making up
the catheter are very small out of necessity.
Also, preferably, the outer section of the cutter can be positioned
so that all of the openings in the outer shell are closed. This
allows the catheter to be inserted into position in an artery
without any exposed sharp edges.
Since the openings in the outer shell are spaced apart, to expose
the entire inner surface to the cutter, the catheter is rotated
slowly while not moving longitudinally until the openings have
covered the entire circumference of the artery. The initial cutting
of plaque occur at the forward openings. The rearward openings act
as gauge cutters to remove the plaque closest to the wall of the
vessel or artery.
Referring again to FIG. 1, the cutter is rotated by shaft 20, which
is a flexible, tubular, member capable of transmitting the desired
torque to the cutter head, such as a reinforced plastic tubing.
Extending through the shaft and connected to the outer shell is
tubular shaft guide 22, also made of reinforced tubing. The shaft
guide must hold the outer shell from rotating with the cutter
blades and to absorb the countertorque produced by the rotating
cutter. The shaft guide is tubular to provide a central opening to
receive the guide wire (not shown) that is usually inserted into
the vein or artery prior to the insertion of the catheter.
Outer tube 24, also made of reinforced tubing, is also connected to
the outer shell and absorbs some of the back-up torque. This tube
has an inside diameter larger than the outside diameter of the
shaft to provide annulus 26. In operation, the pressure in annulus
26 is reduced below ambient pressure to cause blood and the plaque
cuttings to flow from inner annular chamber 28 of the cutter,
through opening 12d in disc 12c, through opening 29a in spacer 29,
through annulus 26, and out of the patient. Reducing the pressure
in chamber 28 also helps pull the plaque into the openings in the
cutter head.
The cutting head and catheter shown in FIGS. 3 and 4 have some
additional features. Shaft 64 and cable guide 66 are connected to
the cutter and outer shell, respectfully. The cutter in this
embodiment has six elongated ribs 70a-70f as shown in FIG. 10. The
ribs are spaced apart by longitudinally extending grooves 72. The
edges of the ribs shave the plaque that protrudes into openings 74
in outer shell 68.
Shaft 64 is attached to the end of cylindrical stub shaft 76 of the
cutter and to cylindrical piezo electric crystal 77 that extends
over the stub shaft and is also attached to the stub shaft.
Cylindrical piezo crystal 78 is cemented to vacuum tube 80 and to
outer shell 68. Lead wire 82 extends along shaft 64 and supplies
electricity to crystal (77) and lead wire 84 extends along vacuum
tube 80 and supplies electricity to crystal 78. It is believed that
the vibration imparted to the cutting head by the crystals when
energized will improve the cutting efficiency of the cutter head,
but, what is more important, the vibrations will help keep the
cutting head from sticking in the artery.
From the foregoing it will be seen that this invention is one well
adapted to attain all of the ends and objects hereinabove set
forth, together with other advantages that are obvious and that are
inherent to the method.
* * * * *